著者: Sheri 日付: To: pcre-dev 題目: Re: [pcre-dev] [Bug 812] Unmatched optional groups do not match
nothing when used as backreference
Philip Hazel wrote: > ------- You are receiving this mail because: -------
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>
> http://bugs.exim.org/show_bug.cgi?id=812 >
> --- Comment #1 from Philip Hazel <ph10@???> 2009-02-22 19:57:51 ---
> Although you say "other regular expressions do this", in fact, Perl does not (I
> checked with Perl 5.008008). PCRE is "Perl-compatible"; it tries to do what
> Perl does. Therefore, I do not think this is a bug. The Perl/PCRE behaviour
> seems fine to me, in any case. \1 matches "what group 1 matched", but if group
> 1 was never used, it didn't match anything - which is not (IMHO) the same thing
> as matching an empty string.
>
>
> I thought this was why you implemented the javascript option.
